While rubber compositions are widely used for industrial applications, a use condition of molded articles using the rubber composition is becoming much more severe, and the development of a high-performance rubber material is a pressing need. For example, in a rubber composition which is used for a pneumatic tire of a car or the like, in order to enhance strength, abrasion resistance, fuel-saving property, and so on, compounded products of a filler, such as carbon black, silica, etc., are used for various purposes. For example, in the case of a tire rubber composition appealing a fuel-saving performance, a silica-based filler is compounded for the filler (see, for example, PTL 1).